1. Field of the Invention
The present invention relates to the delivery of material being transported by a conveyor entraining the material within a flow of fluid, and in particular to the depositing of granular material by a pneumatic conveyor into a storage silo.
2. Background Art
Fluid flow conveyors, particularly pneumatic conveyor systems, have become a popular alternative to augers and belt conveyors for the movement of granular materials. Pneumatic conveyor systems are especially suitable for farm grains for the following reasons: grain is carried within a stream of air for less grain damage; a pneumatic conveyor is more economical to install; a pneumatic conveyor is more versatile for multiple silos and multiple silo types at a storage facility; pneumatic conveyors are sealed against water and pest infiltration between receiving point to delivery of the grain; one pneumatic conveyor system can be utilized to move a variety of grain types without cross contamination, simply by turning a valve distributor between silos; and pneumatic conveyor systems are easier to maintain.
Prior art pneumatic conveyor systems delivering grain to the top of storage silos introduce problems for these systems: a cyclone separator is required for the top of each silo; the entire system is exterior of the silo, exposing the machinery to weather-related damage; exterior supports that may be expensive must be used to support the pneumatic conveyor tubing; roof-mounted supports for the pneumatic conveyor and separator exert forces that tend to pull down the silo and collapse it; much of the pneumatic conveyor system is high above ground and not easily serviced; grain-to-grain damage occurs due to the falling of grain from the silo top to the bottom of the silo, which only increases with the height of the silo; and mixed granular materials experience product separation when dropped from the top of a silo.
Furthermore, an efficiency loss of approximately ten percent for every twenty-five feet (seven and one-half meters) of vertical rise is common to all pneumatic conveyor systems. For example, a pneumatic conveyor system used to fill a silo one hundred feet (thirty meters) tall would operate at 40% less than full efficiency (100 ft×(10%/25 ft)=40% loss; 30 m×(10%/7.5 m)=40% loss).
U.S. Pat. No. 4,082,364, Apr. 4, 1978, to Krambrock describes a method for sequentially filling a series of receiving stations from the tops thereof using a pneumatic conveyor, wherein each station is filled until the surface of the deposited material therewithin is just below the inlet thereof from the pneumatic conveyor and then this surface acts as a deflecting surface to direct the airflow entraining the material onto the next station.
U.S. Pat. No. 1,380,698, Jun. 7, 1921, to Anspach et al. discloses a multistage cyclone separator for a pneumatic conveyor depositing separated material to the same destination, wherein the multistage cyclone separator has at least a lower, upstream cyclone separator and an upper, downstream cyclone separator, and wherein the cyclone separators each has a horizontal inlet aperture through which the air entraining the material horizontally enters therewithin and a helical tube for continuously separating the material from the conveying air simultaneously in all of the cyclone separators.
U.S. Pat. No. 6,632,063, Oct. 14, 2003, to Karlsen et al. describes a system for reducing material segregation between finer and coarser material during filling of a silo from its top by controlling the entraining airflow to be a minimum, wherein the material within the silo as it is being filled can eventually reach the level of the outlet of the system for the material.
U.S. Pat. No. 4,603,769, Aug. 5, 1986, to Bach et al. describes a vertical chute for reducing grain dust with a series of vertically aligned outlets for filling a silo from its top, wherein the deposited grain blocks each outlet sequentially from lower to upper as the silo is filled.
The article Pneumatic Conveying Systems, course No. M05-010, no date, by A. Bhatia of Continuing Education and Development, Inc. discusses the present state of the art of pneumatic conveyors; and defines “choking” as the settling out downwardly of the entrained material from the entraining airflow when the airflow is flowing upwardly vertically in vertically oriented conveying piping, particularly before reaching the conveyor's destination and thus is to be avoided.